1. Field of the Invention
The present invention relates to a cleaning apparatus and a cleaning method for cleaning a substrate, such as a semiconductor wafer.
2. Description of the Related Art
Generally, in the process of manufacturing a semiconductor device, for example, a circuit, an electrode pattern and the like, are formed on a substrate to be processed, such as a semiconductor wafer. In this formation, a series of steps in which a circuit pattern and the like are transferred on a photoresist in a reduced size by a photolithography technique, and the transferred image is developed, are carried out.
In the above-mentioned series of steps, a resist solution is applied on a semiconductor wafer, and then an exposure step and a development step are carried out. However, before the series of preset steps are carried out, it is necessary that the surface of a semiconductor wafer, on which a resist solution is applied for the purpose of avoiding the occurrence of defects in a circuit pattern or the shortcircuit of wiring, should be cleaned and even the rear surface of the semiconductor wafer should be cleaned so as to prevent a focus error during an exposure or the generation of particles.
Such a cleaning apparatus for cleaning a semiconductor wafer is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2-271622. According to the technique discussed in this document, a semiconductor wafer is vibrated so as to remove foreign matters stuck on the semiconductor wafer, and a brush which is rotated at a predetermined rotation speed, is brought into contact with the semiconductor wafer also to remove the foreign matters.
However, in the above-described removing device, the brush which is brought into contact with a semiconductor wafer over the radius of the rotation of the semiconductor wafer, is always rotated at a predetermined rotation speed. With this structure, the rotation moving distance of the semiconductor wafer differs from one point to another over between the center portion of the wafer and the peripheral portion thereof. Therefore, the cleaned surface of the semiconductor wafer is damaged by the rotating brush. Further, due to the difference in the rotation moving distance, the cleaned surface of the semiconductor wafer is irregularly damaged (the degree of damage differs from one location to another on the surface of the wafer, creating an irregular damage).
Moreover, a cleaning solution is supplied from a nozzle, near the brush brought into contact with the wafer. However, the cleaning solution is not supplied to the entire portion of the brush, and a part of the brush is brought into contact with a dry section of the semiconductor wafer, thus further damaging the wafer. Further, since the equal amount of the cleaning solution cannot be supplied to the entire portion of the brush, an irregular treatment of the cleaning occurs in some cases.